K6-266 Compatibility

We have had several requests to test the new AMD K6-266 processor with various motherboards, but have been unable to do so because our shipment was delayed. Today (3/25) we finally received our shipment. Before all of them were packaged up into customer orders, we was able to ‘snag’ one for testing. We were not able to test every motherboard, but did test the more popular ones.

The first two motherboards we tested were the FIC PA-2007 and PA-2012 motherboards. The PA-2007 booted, but the BIOS reported a 80486DX-S processor at 16MHz!! What’s more, it posted a worse Winstone97 result than the K6-233 did – at 233MHz! We searched for an updated BIOS on the FIC website, but were unable to find one. An email has been sent and we hope to hear back by early next week. The PA-2012 would not boot at all with the K6-266 at any voltage or multiplier setting.

The next motherboard tested was the AOpen AX5T-3 using the rev 1.60 BIOS. There is a ‘reserved’ voltage jumper for 2.5/2.1/2.0 volts that we used. This board booted and recognized the K6-266 processor natively, and posted benchmark results about 4% greater than the K6-233 did. Unfortunately, we were unable to test the AP5T-3, however it is almost certain that this board will work as well. This proves that AOpen is one of the premier motherboard manufacturer’s, since the board worked flawlessly with a processor that wasn’t even available at the time the board was developed.

Of course, we had to test the Gigabyte GA586SG and M Tech R581 motherboards, which worked perfectly – as expected. Gigabyte works very closely with AMD, and has a reputation for solid, dependable motherboards. The M Tech board worked very well – and gave us a *very* pleasant surprise, which you can read about in the R581A Update. Believe me, you don’t want to miss that report!

Conclusions

It appears that just having a 2.1v/2.2v jumper on the motherboard does not guarantee it will run this new processor. It will be interesting to see if a new BIOS from FIC corrects the performance problem on the PA-2007. There doesn’t appear to be any way that the PA-2012 will work at all, since the board would not even show the video splash screen with the K6-266.

The performance improvement over the K6-233 is somewhere between 3% and 5%, depending upon which board is used. This is, of course, using the standard 66MHz bus speeds. This alone is probably not enough to make people want to rush out and buy the chip – however, this is the *only* processor we have tested that actually works at 100MHz bus speeds. For those who wish to push their systems to the limit, and want future upgradability on the Socket 7 platform, the K6-266 the only choice at the present time.